In 2005, Gaensler was reported to have solved the mystery of why some supernova explosions form magnetars while others form ordinary pulsars.[6] Later that year, he and his colleagues observed one of the brightest explosions ever observed in the history of astronomy, resulting from a sudden pulse of gamma rays from the magnetar SGR 1806-20.[7] In 2005, Gaensler also reported puzzling new observations of the Large Magellanic Cloud, showing that powerful but unknown forces were at work in maintaining this galaxy's magnetic field.[8]

Gaensler was formerly the international project scientist for the Square Kilometre Array, a next-generation radio telescope. The SKA organisation has since announced that Gaensler is a member of the SKA Magnetism Science Working Group.[9]